Human health risk assessment of groundwater nitrate at a two geomorphic units transition zone in northern China

To assess groundwater nitrate contamination and its human health risks, 489 unconfined groundwater samples were collected and analyzed from Zhangjiakou, northern China. The spatial distribution of principle hydrogeochemical results showed that the average concentrations of ions in descend order was HCO₃^?, SO₄^2?, Na⁺, Ca²⁺, Cl^?, NO₃^?, Mg²⁺ and K⁺, among which the NO₃^? concentrations were between 0.25 and 536.73 mg/L with an average of 29.72 mg/L. In total, 167 out of 489 samples (~ 34%) exceeded the recommended concentration of 20 mg/L in Quality Standard for Groundwater of China. The high NO₃^? concentration groundwater mainly located in the northern part and near the boundary of the two geomorphic units. As revealed by statistical analysis, the groundwater chemistry was more significantly affected by anthropogenic sources than by the geogenic sources. Moreover, human health risks of groundwater nitrate through oral and dermal exposure pathways were assessed by model, the results showed that about 60%, 50%, 32% and 26% of the area exceeded the acceptable level (total health index>1) for infants, children, adult males and females, respectively. The health risks for different groups of people varied significantly, ranked: infants> children> adult males>adult females, suggesting that younger people are more susceptible to nitrate contamination, while females are more resistant to nitrate contamination than males. To ensure the drinking water safety in Zhangjiakou and its downstream areas, proper management and treatment of groundwater will be necessary to avoid the health risks associated with nitrate contamination.     

Bioaugmentation and quorum sensing disruption as solutions to increase nitrate removal in sequencing batch reactors treating nitrate-rich wastewater

Bioaugmentation of denitrifying bacteria can serve as a promising technique to improve nutrient removal during wastewater treatment. While denitrification inhibition by bacterial quorum sensing(QS) in Pseudomonas aeruginosa has been indicated, the application of bacterial QS disruption to improve nitrate removal from wastewater has not been investigated. In this study, the effect of bioaugmentation of P. aeruginosa SD-1 on nitrate removal in sequencing batch reactors that treat nitrate rich wast...     

天然水与28种市售饮用水中"三氮"和磷的调查

2004年8月,测定了海水、黄河水、小清河水、雨水、地下水以及17种瓶装矿泉水、9种瓶装纯净水和北京市、青岛市自来水中的"三氮" (NH 4-N、NO-2-N、NO-3-N) 、无机磷、pH、DO等,发现天然水中NO-3-N过高,水体氮负荷增加,N/P最高达697,雨水pH最低为3.98,部分矿泉水NO-3-N比青岛市自来水还高,北京市自来水的NO-3-N高达8.53 mg/L,为所测饮用水之首.     

Experimental Investigation of Potassium and Nitrate Dynamics in A Headwater Stream in Mid-Wales

Potassium and nitrate were added experimentally to a small moorland stream in the headwaters of the River Wye, mid-Wales, during summer and winter low-flow conditions. Nutrient losses at three downstream sampling locations were calculated using concentrations of an added bromide tracer to correct for dilution effects. During the summer experiment, approximately 18% of the added nitrate and 58% of the potassium were removed from the stream water between the point of addition and the catchment outlet. During the winter experiment, nitrate depletion was not observed and the added nitrate travelled along the stream at the same rate as the bromide tracer, while approximately 93% of the added potassium passed through the stream but, at a slower rate than the bromide and nitrate. the results show that in-stream processes, probably related to biological activity of macrophytes and microflora, can regulate stream water concentrations of nitrate and potassium in the summer under stable flow conditions. During the winter, no removal of nitrate or potassium was observed but ion exchange processes involving biofilms, Sphagnum and/or stream sediment may explain the temporary retention of potassium within the stream channel. If similar ion exchange processes operate at high flows, they may account for the hysteresis relationship observed between potassium and discharge during storm events in many upland streams.     

Surface-enhanced Raman scattering for mixing state characterization of individual fine particles during a haze episode in Beijing, China

The nondestructive characterization of the mixing state of individual fine particles using the traditional single particle analysis technique remains a challenge. In this study, fine particles were collected during haze events under different pollution levels from September 5 to 11 2017 in Beijing, China. A nondestructive surface-enhanced Raman scattering (SERS) technique was employed to investigate the morphology, chemical composition, and mixing state of the multiple components in the individual fine particles. Optical image and SERS spectral analysis results show that soot existing in the form of opaque material was predominant during clear periods (PM_2.5 ≤ 75 µg/m³). During polluted periods (PM_2.5 > 75 µg/m³), opaque particles mixed with transparent particles (nitrates and sulfates) were generally observed. Direct classical least squares analysis further identified the relative abundances of the three major components of the single particles: soot (69.18%), nitrates (28.71%), and sulfates (2.11%). A negative correlation was observed between the abundance of soot and the mass concentration of PM_2.5. Furthermore, mapping analysis revealed that on hazy days, PM_2.5 existed as a core-shell structure with soot surrounded by nitrates and sulfates. This mixing state analysis method for individual PM_2.5 particles provides information regarding chemical composition and haze formation mechanisms, and has the potential to facilitate the formulation of haze prevention and control policies.     

North East Scotland River Catchment Nitrate Loading in Relation to Agricultural Intensity

Modern agricultural practices have been strongly linked with increased NO₃-N loadings in surface waters. Nitrate leaching increases as land use progresses from forest and moorland through grassland, to arable agriculture. There are, within the UK, few studies on a regional scale capable of displaying a relationship between land cover (agricultural intensity) and water quality. This relationship can be investigated using computer manipulation of spatial geographic information together with conventional river and agricultural census data.

Simple regression analysis against primary land cover suggests that agriculture is reponsible for annual losses of nitrate in North East Scotland river catchments. Further multi-linear regression analysis, using the GIS data and agricultural census returns indicate that most of the outstanding variation can be accounted for if the agricultural variable is related to agricultural practice, such as spring, winter and grass cropping.     

Nitrate Status of Two Major Rivers in N. E. Scotland with Respect to Land Use and Fertiliser Additions

Land Use and the influence it has upon river water nitrate levels is discussed, for two large relatively unpopulated river systems in the N.E. of Scotland. the catchment areas for the rivers Dee and Don have been further subdivided into a number of sub catchments. Substantial differences in land use and agricultural potential exist both within and between the two areas. Greater agricultural production down stream is associated with increased river nitrate concentrations.     

Distribution of nitrogen species in groundwater aquifers of an industrial area in alluvial Indo-Gangetic Plains—a case study

The groundwater samples collected from the shallow and deep groundwater aquifers of an industrial area of the Kanpur city (Uttar Pradesh, India) were analyzed for the concentration levels and distribution pattern of nitrogenous species, such as nitrate-nitrogen (NO₃-N), nitrite-nitrogen (NO₂-N), ammonical-nitrogen (NH₄-N), organic-nitrogen (Org-N) and total Kjeldahl-nitrogen (TKN) to identify the possible contamination source. Geo-statistical approach was adopted to determine the distribution and extent of the contaminant plume. In the groundwater aquifers NO₃-N, NO₂-N, NH₄-N, TKN, Org-N and Total-N ranged from 0.10 to 64.10, BDL (below detection limit)-6.57, BDL-39.00, 7.84–202.16, 1.39–198.97 and 8.89–219.43 mg l⁻¹, respectively. About 42% and 26% of the groundwater samples of the shallow and deep groundwater aquifers, respectively, exceeded the BIS (Bureau of Indian Standards) guideline value of 10 mg l⁻¹ for NO₃-N and may pose serious health hazards to the people of the area. The results of the study revealed that the groundwater aquifers of the study area are highly contaminated with the nitrate and indicates point source pollution of nitrate in the study area.     

Seasonal dynamics of labile soil nitrogen from four plantations at the western edge of the Sichuan Basin北大核心CSCD

The objective of this study was to investigate the soil nitrogen components of four native artificial plantations at the western edge of the Sichuan Basin. Soil samples from two layers (0-20 cm and 20-40 cm) were collected from 4 plantations (Cryptomeria fortunei, Michelia wilsonii, Phoebe zhennan, and Quercus acutissima) during March, June, September, and December 2015 at the western edge of Sichuan Basin, to perform a comparative analysis on seasonal dynamics. Soil ammonium, nitrate, microbial biomass nitrogen, and environmental factors were synchronously monitored. The results showed that soil inorganic nitrogen was mainly the result of nitrate. The components of labile soil nitrogen showed significant seasonal dynamics. Soil ammonium during the growing season (June and September) was higher than that during the non-growing season (March and December), but soil nitrate, microbial biomass nitrogen, and inorganic nitrogen showed the opposite pattern. Labile nitrogen components in the 0-20 cm layer were generally higher than those in the 20-40 cm layer. Labile soil nitrogen was significantly affected by forest type, which was dependent on season and soil layer. In general, there were significant correlations between the soil nitrogen pools and labile soil nitrogen and the environmental factors, including soil temperature, water content, and monthly rainfall. In conclusion, the variation of labile soil nitrogen was influenced more by season than forest type or soil layer. Compared to the biological effects of tree species, the environmental factors had a stronger effect on labile soil nitrogen. © 2018 Science Press. All rights reserved.     

Multi-criteria decision analysis for the optimal management of nitrate contamination of aquifers

We present an integrated methodology for the optimal management of nitrate contamination of ground water combining environmental assessment and economic cost evaluation through multi-criteria decision analysis. The proposed methodology incorporates an integrated physical modeling framework accounting for on-ground nitrogen loading and losses, soil nitrogen dynamics, and fate and transport of nitrate in ground water to compute the sustainable on-ground nitrogen loading such that the maximum contaminant level is not violated. A number of protection alternatives to stipulate the predicted sustainable on-ground nitrogen loading are evaluated using the decision analysis that employs the importance order of criteria approach for ranking and selection of the protection alternatives. The methodology was successfully demonstrated for the Sumas-Blaine aquifer in Washington State. The results showed the importance of using this integrated approach which predicts the sustainable on-ground nitrogen loadings and provides an insight into the economic consequences generated in satisfying the environmental constraints. The results also show that the proposed decision analysis framework, within certain limitations, is effective when selecting alternatives with competing demands.